MOS silicon gate technology defines an MOS transistor location by a field oxide opening, and defines the MOS channel region location by a polysilicon gate electrode overlying this opening. The width of the polysilicon (poly) determines the channel length L, and the width of the field oxide opening determines the channel width W. The poly is made longer than the channel width to allow for misalignment tolerance. For a very narrow sub micron channel width this tolerance can be almost as large as the width. Furthermore, if a metal connection is to be made to the poly, the poly has to extend even further beyond the channel width to make room for a contact hole to the metal. These considerations can severely limit the circuit layout density of very small transistors.